Table 2.
Standardized experimental methodologies for assessing behavioral effects of prenatal alcohol exposure in murine models.
| Skills affected by PAE | Disorders | Behavioral test | Description |
|---|---|---|---|
| Motor skills Cerebellum (Purkinje cells) (254) |
Motor hyperactivity, poor motor coordination, altered accuracy of saccadic eye movements, and deficits in postural balance are impaired motor skills observed in individuals exposed to ethanol during early life. PAE-related motor deficits are more apparent in early life than in adulthood. |
The rotarod (79) | For this test, a bar that can rotate at an accelerated or a fixed speed is used. The latency of the fall of the rodent placed in the bar is measured. Measurements provide an idea of motor coordination. |
| Swimming test (255) | It consists of a Perspex tank where rodents are placed and must swim to an escape platform. The sequence is recorded and later analyzed to assess the latency to reach the platform and the number of fore and hind limb strokes. | ||
| Raised beam test | Rodents are placed on the bar and their ability to cross it is measured along with paw slips and traverse time. It provides an indication of their balance. | ||
| Footprint analysis | After their paws are painted or dipped in ink, rodents leave a trail of footprints when they walk or run along a corridor to a goal box. Measurements of stride length, base width, and fore and hind paws overlap give an indication of gait. Automated versions of the task use video processing of footage taken from below the rodents. | ||
| Learning and memory Hippocampus (dentate gyrus) (256, 257) |
Hippocampal cell loss, altered neuronal morphology, decreased synaptic density, and reduced trophic support. | Simple maze task (258, 259) | A T-maze (or the variant Y-maze) is a simple maze used in animal cognition experiments. It is shaped like the letter T (or Y), providing the subject, typically a rodent, with a straightforward choice. T-mazes are used to study how rodents function with memory and spatial learning by applying different stimuli. The different tasks, such as left-right discrimination and forced alternation, are mainly used with rodents to test reference and working memory. |
| Morris water maze (71, 252) | MWM is a test of spatial learning for rodents that relies on distal cues to navigate from a start point around the perimeter of an open swimming box to locate a submerged escape platform. The test allows measuring spatial learning and reference memory. | ||
| Fear conditioning (260) | This test is a form of Pavlovian learning based on the conditioning of an innate response to fear consisting in a complete lack of movements. During an initial phase, the animal is exposed to a conditioned stimulus paired with an aversive experience (unconditioned stimulus). The test measures the fear response in mice replaced in the same location with and without the previous stimulus. | ||
| Object recognition (79, 261) | In an initial session, the rodent is presented with two similar objects. One of the objects is replaced by a new object in the second session. The test measures the amount of time taken to explore the new object. | ||
| Executive function frontal cortex and extra-frontal cortex (262) | Disorders in cognitive control of behavior, including basic cognitive processes such as attentional control, cognitive inhibition, inhibitory control, working memory, and cognitive flexibility. | Passive avoidance (263) | Mice learn to inhibit the natural tendency to explore new environments where a negative stimulus was previously obtained. The test consists of a chamber divided in two compartments separated by a gate. Animals are allowed to explore both compartments in the initial phase. In the following phase, they obtain a negative stimulus in one of the compartments. Animals will learn to associate certain properties of the chamber with the negative stimulus. The test measures the latency to cross the gate between the two compartments when the animal is placed in the compartment where no aversive stimulus were obtained. |
| Simple maze task (258, 259) | See description in learning and memory. | ||
| Morris water maze (71, 252, 264) | See description in learning and memory. | ||
| Prepulse inhibition (265) | PPI is a neurological phenomenon in which a soft pre-stimulus (pre-pulse) inhibits the reaction of the animal to a subsequent strong stimulus (pulse) often using the startle reflex. Stimuli may be acoustic, tactile, or luminous. | ||
| Social behavior (251) | Poor social skills and inappropriate social interactions. | Observation (251) | Feeding difficulties in neonates and lack of parental care. Aggressive behaviors in adults and reversed behaviors between males and females. |
| Affective behavior (201) | Anxiety- and depressive-like behaviors (201) | Elevated-plus maze (266) | The device is made up of open arms and closed arms, crossed in the middle perpendicularly to each other. Mice have access to all of the arms. The number of entries into the open arms and the time spent in each arm are used as a measure of anxiety-like behavior. |
| Forced-swim test (267) | The test is based on the assumption that an animal placed in a container filled with water will try to escape. However, it will eventually exhibit immobility that may be considered a measure of depressive-like behavior. | ||
| Olfaction (253) | Injury of the olfactory circuits. | Classical conditioning tasks (268) | An odor is paired with a tempting or aversive stimulus and the response of the animal to the odor is followed by the tester. |
PAE, prenatal alcohol exposure.